Flexible Resistive Gas Sensor Based on Molybdenum Disulfide-Modified Polypyrrole for Trace NO₂ Detection

Area of Science:

• Materials Science
• Chemical Engineering
• Sensor Technology

Background:

• Conductive polymer gas sensors, like polypyrrole (PPy), face limitations in sensitivity, selectivity, and response time for practical applications.
• Poor stability and long response times hinder the widespread use of single-phase conductive polymers.

Purpose of the Study:

• To develop and characterize flexible PPy/MoS2 composite thin-film sensors for enhanced NO2 detection.
• To investigate the performance improvements in sensitivity, selectivity, and stability compared to pure PPy sensors.

Main Methods:

• Fabrication of flexible PPy/MoS2 composite films using chemical polymerization and mechanical blending.
• Construction of resistive NO2 sensors on a polyimide substrate using a flexible electronic printer.
• Characterization of composite films via X-ray diffraction, FTIR, and FESEM.
• Gas sensing performance evaluation using a home-built test platform.

Main Results:

• The PPy/MoS2 sensor demonstrated significantly higher sensitivity (38% response to 50 ppm NO2 at 150 °C, a 26% increase over pure PPy).
• Enhanced selectivity and stability were observed for the PPy/MoS2 composite sensor compared to the pure PPy sensor.
• Improved performance is attributed to p-n heterojunction formation and increased gas adsorption sites.

Conclusions:

• PPy/MoS2 composite films offer a promising material for developing high-performance flexible gas sensors.
• The fabricated sensors exhibit excellent potential for practical NO2 sensing applications due to improved characteristics.